Miniaturized Angularly Stable Single and Dual Bands Bandpass Frequency Selective Surfaces with Transmission Zeros Near the Sidebands
Soumik Dey, Mohammad Abdul Shukoor, Sukomal Dey
Abstract
This paper presents two single-layer miniaturized bandpass frequency selective surfaces (FSSs) with single and dual-band resonances. Transmission zeros (TZs) are introduced near to the sidebands which in effect improve the filter selectivity at the resonance. The basic FSS prototype consists of a capacitive grid (CG) loaded cross-dipole aperture (CDA) which shows a passband center at 6.22 GHz with a 3 dB bandwidth (BW) of 20.3 %. Later the CG structure is modified by adding parallel slot lines (PSL) which are extended towards the center to realize the second FSS unit cell. The proposed FSS-2 exhibits closely spaced dual passbands center at 5.5 and 7.48 GHz with a frequency ratio of 1.36. Passband insertion losses at two frequencies are 0.19 and 0.46 dB with BWs of 31.7 and 13.5 %. The proposed single and dual-band FSSs show polarization insensitive filter response with oblique angle stability of 40° and 55° respectively.